Apparatus for transforming rotational rates into fluid signals



APPARATUS FOR TRANSFORMING ROTATIONAL RATES INTO FLUID SIGNALS Filed May4, 1966 L. B. TAPLIN Aug. 25, 1970 2 Sheets-Sheet l an-1- .J

/Z 12 Z 7034mm? L. B. TA PLIN Aug. 25, 1970 APPARATUS FOR TRANSFORMINGROTATIONAL RATES INTO FLUID SIGNALS Filed May 4. 1966 2 Sheets-Sheet 2INVENTOR Q w E- United States Patent 3,525,488 APPARATUS FORTRANSFORMING ROTATIONAL RATES INTO FLUID SIGNALS Lael B. Taplin,Livonia, Mich., assignor to The Bendix Corporation, a corporation ofDelaware Filed May 4, 1966, Ser. No. 547,595

Int. Cl. Fc 1/16; B64c 13/36, 13/40 US. Cl. 244-78 16 Claims ABSTRACT OFTHE DISCLOSURE Apparatus for transforming rotational rates into fluidsignals which actuate a fluid control device to maintain the wings of anaircraft level in flight. A pair of vortex rate sensors having parallelaxes and a common supply are connected to the fluid control device sothat the outputs from the sensors actuate the control device. Each ratesensor has a biasing vortical flow in a direction opposite to the othersensor such that a rotation imparted to the pair by wing movement willreinforce the vortical flow in one and subtract from the vortical flowin the other to provide a constant combined demand upon the supply and adifference in outputs which is used to actuate the control device.

This invention pertains to fluid apparatus for transforming rotationalrates into fluid signals and more particularly to apparatus for sensingrotational rates of aircraft, which indicate change in the attitude anddirection of the aircraft to provide a correction signal to the controlsof the aircraft to reestablish the original attitude and direction ofthe aircraft.

It is an object of this invention to provide a relatively simple,inexpensive, flight control automatic pilot system for aircraft whichdoes not require expensive gyros. This object is accomplished byproviding fluid rotational rate sensor apparatus using a fluid vortexdevice as disclosed and described in copending application to Endre A.Mayer, Ser. No. 458,619, filed May 25, 1965, entitled Fluid Device. Theoutput of the fluid rate sensor apparatus is amplified and then utilizedto operate the aircraft controls.

It is a further object of this invention to provide a simple,inexpensive, flight control for aircraft which does not require apressure regulator for the fluid system. This object is accomplished inthe preferred embodiment by utilizing two vortex rate sensors with acommon input passage for both, providing means for biasing one of thevortex rate sensors with a vortical flow in one direction and biasingthe other of the vortex rate sensors with a vortical flow in theopposite direction so that for a given rotation of the aircraft, theimparted rotation to one sensor will reinforce the biasing flow whilethe imparted rotation to the other sensor will subtract from the biasingflow. In this manner, as the output pressure of one sensor drops, theoutput pressure of the other sensor will increase making the fluiddemand from the common supply passage substantially constant, therebymaking a regulated fluid supply unnecessary.

It is an object of this invention to amplify each of the vortexrotational rate sensors of the previous objects with additional vortexfluid devices and then utilizing the amplified signal to operate thecontrol of an aircraft or other device. It is an additional object ofthis invention to utilize additional tangential vortex producing controlsystems, which are generated by instruments such as magnetic compass,preset heading, altimeter, glide scope and track and capture, toaccordingly modify the output of the vortex amplifier.

These and other objects will become more apparent when preferredembodiments of this invention are considered in connection with thedrawings in which:

FIG. 1 is a diagrammatic schematic view of a fluid control system ofthis invention;

FIG. 1a is a diagrammatic view of a control system placed in anaircraft;

FIG. 2 is a diagrammatic sectional view of the rotational rate sensorsutilized in a preferred embodiment of this invention;

FIG. 2a is a section taken at 2a2a of FIG. 2 showing the tangentialcontrol jets;

FIG. 3 is a graph showing typical output characteristics of the sensor;

FIG. 4 is a diagrammatic sectional view of a vortex amplifier used in apreferred embodiment of this invention;

FIG. 5 is a diagrammatic schematic of a vortex amplifier having aplurality of control inputs, each of which modifies the amplifieroutput;

"FIG. 6 is a graph showing a typical characteristic curve of the deviceof FIG. 5 showing the influence of the additio'r'ial control streams onthe output; and

BIG. 7 is a diagrammatic view of an instrument, such as'a compass, andmeans for generating a pressure which is proportional to the heading ofthe magnetic compass.

FIG. 1 is a schematic diagram showing fluid system 20 for an aircraftthat can automatically hold the wings level in aircraft flight when thesensitive axis of the rate sensor is oriented to sense combined vehicleyaw and roll rate. A rotational rate sensor 22 is shown in more detailin FIG., 2 and a vortex fluid amplifier 2 4 is shown in more detail inFIG. 4. Before describing the schematic of'FIG. 1, the rate sensor inFIG. 2 and the amplifier in FIG. 4 will be described.

RAT'E SENSOR 22 (FIG. 2)

In the schematic of FIG. 2 is shown a cup shaped housing 26 having achamber outlet 28 formed centrally thereof." The outlet 28 is connectedto vacuum chamber 30 which has connected thereto a plurality of vacuumvents 32"'which are connected to vacuum pump 72 through valve 33.Located centrally of vacuum chamber 30 and axially aligned with chamberoutlet passage 28 is external pickotf tube 34. Also formed in housing 26circumferentially thereof are a plurality of nozzles 36 which directfluid tangentially into the interior of housing 26 along innercircumference 37 thereby creating a vortical flow. A control inlet 38(FIG. 2a) is also formed in housing 26 and supplies fluid to nozzles 36through annulus 39. A button 40 is supported centrally in housing 26 andis spaced therefrom to form vortex chamber 42. A porous annulus 44 isformed between the outer circumference of button 40 and circumference 37and aids in the rate sensing capabilities. A cover 46 is attached to andsupports button 40 and is connected to housing 26.

An internal pickofl passage 48 is formed centrally in button 40 andcommunicates through fluid line 50 to external pickoff tube 34. Supplyinlet 52 is formed through cover 46 and provides an entrance for supplyfluid which flows through restricted orifice 54.

Frequently a supply pressure greater than atmospheric pressure isapplied to inlet 52; however, in this embodiment, the same effect isobtained by drawing a vacuum on vacuum vents 32 by means of vacuum pump72 which will cause a flow through orifice 54, and control inlet 38 dueto atmospheric pressure outside of sensor 22. A pressure drop occursacross orifice 54, and therefore the supply pressure P in supply inlet52 is less than the control pressure P which is in inlet tube 38. Thiscauses a constant bias swirl in vortex chamber 42 and this bias swirlcenters the operation of the device in the maximum gain portion of itsinput-output curve.

The flow from chamber 42 passes into vacuum chamber 30 through outputpassage 28 and then through vacuum vent 32. Valve 33 may be used toadjust the pressure in chamber 32. A fluid flow which is counter to thatin passage 28 is developed in external pickolf tube 34 due to the higherpressures in internal pickoff passage 48. A valve 56 is located in line50 and may be adjusted to achieve desired gain and noisecharacteristics.

As sensor 22 is rotated, as would be the case if it were fixed on arotation axis in an aircraft and the aircraft rotated about the axis, aswirl of air is induced in chamber 42 causing the output pressure P inthe tube 34 to either increase or decrease, according to the directionof the rotation. Porous coupling element 44 aids in the swirling of airin chamber 42 when the sensor 22 is rotated. The curve shown in FIG. 3plots Rotational Rate Input vs. Pressure Output and was obtained for adevice similar to that shown in FIG. 2 and described above. Sensor 22ais essentially identical to sensor 22 except the biasing vortical flowis in the opposite direction.

AMPLIFIER 24 (FIGURE 4) The amplifiers 24, 2411 are similar inconstruction to the sensor in FIG. 2 and only amplifier 24 is shown inFIG. 4. Parts in amplifiers 24, 24a, which are similar to parts insensor 22 carry similar reference numerals and are suflixed by theletters b and 0 respectively. The amplifier in FIG. 4 has its controlport 38b connected to the output of rate sensor 22. Further, amplifiers24, 24a do not have a porous coupling element 44.

The operation of amplifier 24 is similar to the operation of sensor 22with the major difference being in the manner of obtaining controlvortical flow in chambers 42b, 42 respectively. In sensor 22, thecontrol vortical flow is obtained by rotating the sensor while inamplifier 24, the control vortical flow is obtained from the fluidoutput of sensor 22.

EMBODIMENT OF FIGURE 1 In the schematic of FIG. 1, rate sensors 22, 22aare mounted so that their axes of the vortex chambers are aligned withthe axis of the vehicle such as an aircraft about which the rotation isto be sensed. The output of rotational rate sensor 22 is connected totangential control port 38b of amplifier 24 and the output of rotationalrate sensor 22a is connected to tangential control port 38c of amplifier24a. Variable orifices 39b and 39c may be used to control the overallsystem gain. Also, several additional amplifiers may be connected inseries to each of amplifiers 24, 24a to increase overall gain.

The output of amplifier 24 is connected to an upper bellows chamber 62of a pneumatic control 60 while the output of amplifier 24a is connectedto a lower bellows chamber 64 of pneumatic control device 60. Betweenbellows chamber 62, 64 is control arm 66 which has control cables 68, 70connected thereto and movable thereby. As will be seen, when anincreased pressure is applied to bellows chamber 62, a correspondingreduced pressure will be applied to bellows chamber 64 thereby movingarm 66 in a downward direction and causing control cables 68, 70 to becorrespondingly moved. Likewise, when an increased pressure is appliedto chamber 64 by amplifier 24a, a corresponding reduced pressure will beapplied to bellows chamber 62 by amplifier 24 thereby moving control arm66 and control cables 68, 70 in an upward direction.

Under quiescent conditions, the outputs of rate sensors 22, 22a willhave an output signal that will bias the quiescent operating position ofamplifiers 24, 24a respectively to approximately the mid point of thehigh gain section of their input-output curve. Therefore, there will bean output pressure delivered by amplifiers 24, 24a to bellows 62, 64respectively under quiescent, or no signal, conditions which pressurewill balance arm 66 in a neutral position.

Vacuum pump 72 is connected to vacuum chamber vents 32, 32a, 32b, 32cand provides the operating pressures for the rate sensors 22, 22a andamplifiers 24, 24a.

Orifice 54b restricts the supply lines 5217, 520 of amplifiers 24, 24athereby reducing the pressure in lines 52b, 520 to a value less thanthat in lines 38b, 380 to provide the desired control bias.

With orifice 54 reducing the pressure in lines 52 and 52a below thecontrol line pressures 38, 38a, the fluid devices 22, 22a are properlybiased for no signal mid point operation on the high gain portion oftheir curves. In this preferred embodiment, rate sensors 22, 22a arecoaxial, in fixed relation to each other and to the vehicle in whichthey are mounted. The biasing ports 38 are directed so that a clockwisevortical flow occurs in sensor 22 and the biasing ports 38a are directedso that a counter clockwise vortical flow occurs in sensor 22a under nosignal conditions. Hence, any rotation of the vhicle about the axis ofsensors 22, 22a will reinforce the vortical flow in one of the sensorsand diminish the vortical flow in the other of the sensors therbyrespectively decreasing the output pressure in one of the sensors andincreasing the output pressure in the other of the sensors so that thetotal of the output pressures of both sensors remains approximately thesame during all operating conditions. This means that the fluid demandthrough orifice 54, which is connected to atmosphere, will remainsubstantially constant and therefore a pressure regulator and a pressureregulator system is unnecessary, further reducing the costs and furthersimplifying this system. Without the dual sensors having oppositevortical flows, pressure regulation would be necessary since a change inoutput pressure would otherwise change supply pressure which would alterthe relationship between the bias pressure control and thereby alter thebias flow.

To obtain maximum gain in the rate sensors 22, 22a and amplifiers 24,24a, the external pickoffs 34 to 340 are connected, respectively, to theinternal pickoffs 48 to 480. However, the external pickolfs may be usedin isolated circuits as described in copending Mayer application.

Also, multiple stages may be used in both the sensors 22, 22a and theamplifiers 24, 24a. 'Ihis cascading of stages would increase the sensingand amplification to levels desired for particular applications.

While sensors 22, 22a have been described as correct aircraft attitudeand direction errors, they may also be used to receive a command signalfrom the pilot to effect a change in aircraft position. This may beaccomplished by introducing pilot controlled pressure changes to fluidcontrol supply 37 to change the pressure in either or both of chambers62, 64, moving control 66. Preferably, for a given command signal, thesignals to tubes 38, 38a are equal in magnitude but opposite indirection, thereby making a pressure regulation unnecessary.

EMBODIMENT OF FIGURE 5 If desired, additional inputs may be made to theamplifiers 24, 24a for adding to or subtracting from the control inputssignals in lines 38b, 380. This is shown in the schematic of FIG. 5where amplifier 24 is shown schematically and supply presure P is shownat line 5212. Five separate inputs C-l to 0-5 are shown connectedtangentially to the outer circumference of amplifier 24. A controlpressure source P shown at is fed through pressure modifying devices 82to which may add to or subtract from the signal going to vehicle control60. The graph of FIG. 6 shows the output pressure plotted against theinput pressure for various combinations of control pressures C-l to C-5.

The fluid pressure control devices 82 to 90 may include a magneticcompass control, an adjustable heading card control for providing apilot with a preselected heading hold set point which may be changedduring flight, VOR navigation devices for cross country flying andlanding approaches with a VCR track added by means of a pneumaticinterface with an OMNI coupler, an altimeter for altimeter hold functionand a display for a turn and bank indicator.

An example of how these pressure control devices 82 to 90 may beimplemented is shown in the schematic of FIG. 7. A magnetic compass 92has a shaft 94 which is fixed to the compass needle 95 and movedtherewith and carries on the end thereof a cam 96. Cam 96 is positionedin the fluid path from nozzle 98 and therefore varies the fluid pressurein nozzle 98 as the cam is turned, moving closer or further away fromnozzle 98, respectively increasing and decreasing the pressure in nozzle98. Output line 100 from nozzle 98 could then be connected to a controlinput of an amplifier 24, 24a for an auxiliary control to the auto pilotshown in the schematic of FIG. 1. In like manner, other instrumentscould be implemented for use with this invention.

Although this invention has been disclosed and illustrated withreference to particular applications, the principles involved aresusceptible of numerous other applications which will be apparent topersons skilled in the art. For example, the principles of thisinvention may be applied to machine controls as Well as to vehiclecontrols. The invention is, therefore, to be limited only as indicatedby the scope of the appended claims.

Having thus described my invention, I claim:

1. Apparatus comprising:

first fluid rotational rate sensing means having an input flow to achamber for fluid vortexes, and an output flow from the chamber forfluid vortexes, said rate sensing means receiving a supply flow at itsinput and discharging a fiow at its output in proportion to therotational rate being experienced by said rate sensing means due to thevortical flow in said rate sensing means caused by the rotational rateexperienced by said rate sensing means, first biasing means forinjecting a biasing vortical flow in one direction in said first fluidrate sensing means to cause said sensing means to operate during nonrotation conditions at a predetermined point on the input-output curveof the sensing means so that rotational rates in one direction willcause the operating point to move in one direction on said input-outputcurve and rotational rates in the opposite direction will cause theoperating point to move in the opposite direction on said input-outputcurve, second fluid rotational rate sensing means having an input flowto a chamber for fluid vortexes and an output flow from the chamber forfluid vortexes,

said rate sensing means receiving a supply flow at its input anddischarging a flow at its output in proportion to the rotational ratebeing experienced by said second rate sensing means due to the vorticalflow caused in said second rate sensing means by the rotational rateexperienced by said rate sensing means,

second biasing means for injecting a biasing vortical flow in saidsecond rate sensing means in a direction opposite to the direction ofthe vortical flow of said first biasing means and to cause said sensingmeans to operate during non rotation conditions at a predetermined pointon the input-output curve of the sensing means so that rotational ratesin one direction will cause the operating point to move in one direction:on said input-output curve and rotational rates in the oppositedirection will cause the operating point to move in the oppositedirection on said input-output curve,

common fluid supply means for providing supply pressure for said firstand second fluid rotational rate sensing means.

2. The apparatus of claim 1 with fluid amplifier means for amplifyingthe outputs of each of said fluid rotational rate sensing means.

3. The apparatus of claim 1 with amplifier means for amplifying theoutputs of each of said fluid rotational rate sensing means,

said amplifier means being fluid vortex amplifiers.

4. The apparatus of claim 2 with means for supplying additional fluidinputs to said amplifier means and thereby modify the amplifier outputsignal.

5'. The apparatus of claim 4 with vehicle control means,

the output of one amplifier means being connected to move said controlmeans in one direction and output of the other amplifier means beingconnected to move said control means in said one direction for the samerotational direction applied to said first and second rotational rateamplifiers.

6. The apparatus of claim 1 with each of said first and secondrotational rate sensing means comprising a cylindrical chamber having asupply port means for admitting gaseous flow to said chamber,

each of said first and second rotational rate sensing means having anexhaust port formed axially of the cylindrical chamber,

biasing port means being placed circumferentially of each of saidcylindrical chambers,

an output piokoff tube spaced axially from each of said exhaust portswith a vacuum chamber being between each of said exhaust ports and anoutput pickoff tube,

means to apply a pressure to each of said output pickoff tubes to causea flow in said output pickoff tube which is counter to the flow in saidexhaust ports,

means to apply a reduced pressure to said vacuum chambers therebycausing a flow into said cylindrical chambers from said supply portmeans and said biasing port means,

restriction means being in said supply port means so that the pressurein said biasing port means will be higher than that in said supply portmeans.

7. The apparatus of claim 6 with said means to apply a pressure to saidoutput pickoff tubes comprising a connection to the center of therespective cylindrical chamber.

-8. The apparatus of claim 6 with amplifying means connected to theoutputs of each of said fluid rate sensing means,

said amplifying means comprising cylindrical chambers having supply portmeans for supplying the amplifying means cylindrical chambers with afluid flow,

control port means arranged circumferentially of said amplifying meanscylindrical chambers and connected to the outputs of said first andsecond rotational rate sensing means,

said amplifying means having exhaust ports axially disposed of theamplifying means cylindrical chambers.

9. The apparatus of claim 8 with said amplifying means having pickofftubes spaced axially of said exhaust ports with vacuum chamberstherebetween,

means to apply a reduced pressure to said vacuum chambers therebycausing a flow into said cylindrical chambers from said supply portmeans and said control port means,

restriction means being in said supply port means so that the pressurein said biasing port means will be higher than that in said support portmeans.

10. The apparatus of claim 6 with porous means being in said fluidchamber of each of said first and second rate sensing means to moreefficiently move the fluid in said rate sensing means when said ratesensing means are rotated.

11. Apparatus comprising first fluid means having an input flow to achamber for fluid vortexes and an output flow from the. chamber forfluid vortexes,

said fluid means receiving a supply flow at its input 7 and discharginga flow at its output in proportion to the vortical flow in said fluidmeans,

first biasing means for injecting a biasing vortical flow in onedirection in said first fluid means to cause said fluid means to operateduring no signal conditions at a predetermined point on the input-outputcurve of the sensing means so that a. vortical flow less than said nosignal condition will cause the operating point to move in one directionon said input-output curve and a vortical flow greater than said nosignal condition will cause the operating point to move in the oppositedirection on said inputoutput curve,

second fluid means having an input flow to a chamber for fluid vortexesand an output flow from the chamher for fluid vortexes,

said fluid means receiving a supply flow at its input and discharging aflow at its output in proportion to the vortical flow in said secondfluid means,

second biasing means for injecting a biasing vortical flow in saidsecond fluid means in a direction opposite to the direction of thevortical flow of said first fluid means and to cause said second fluidmeans to operate during no signal conditions at a predetermined point onthe input-output curve of the second fluid means so that a vortical flowless than said no signal condition will cause the operating point tomove in one direction on said input-output curve and a vortical flowgreater than said no signal condition will cause the operating point tomove in the opposite direction on said input-output curve,

common fluid supply means for providing supply pressure for said firstand second fluid means,

signal means supplying substantially equal and opposite flows to saidfirst and second fluid means so that when the biasing vortical flow inthe first fluid means is aided, the biasing vortical flow in the secondfluid means will be diminished, thereby making a pressure regulatorunnecessary.

12. The apparatus of claim 11 with vehicle control means,

the outputs of said first and second fluid means being connected to saidvehicle control means.

13. In control apparatus for a craft having at least one axis aboutwhich rotation is to be sensed,

a pair of craft movement responsive fluid vortex rate sensors, each ofwhich includes a vortex chamber having an axis and means in said chamberfor imparting vortical flow to fluids therein in response to rotationthereof about said axis,

means for introducing supply fluid to said chambers from a common sourceat a predetermined supply pressure, and

means, separate from said means for introducing supply fluid, forintroducing biasing fluid to each of said chambers at a predeterminedpressure which is greater than said supply pressure to induce a biasingvortical flow of the fluid therein about the axis thereof in an oppositedirection in one chamber from the flow in the other,

said rate sensors being mounted so that said vortex chamber axes areparallel for location in positions on said craft in which said chamberaxes have components parallel to said craft axis so that movement ofsaid craft about said axis causes additional vortical movement of thefluid in one of said chambers and 8 reduced vortical movement of thefluid in the other one of said chambers whereby the diflerence in theoutput pressures from said sensors is related to the rate of rotation ofsaid craft about said axis.

'14. In control apparatus for a craft having at least one axis aboutwhich rotation is to be sensed,

a pair of craft movement responsive fluid vortex rate sensors, each ofwhich includes a vortex chamber having an axis and means in said chamberfor imparting vortical flow to fluids therein in response to rotationthereof about said axis,

means for introducing supply fluid to said chambers from a common sourceat a predetermined supply pressure,

means, separate from said means for introducing supply fluid, forintroducing biasing fluid to each of said chambers at a predeterminedpressure which is greater than said supply pressure to induce a biasingvortical flow of the fluid therein about the axis thereof in an oppositedirection in one chamber from the flow in the other,

said rate sensors being mounted so that said vortex chambes axes areparallel for location in positions on said craft in which said chamberaxes have components parallel to said craft axis so that movement ofsaid craft about said axis causes additional vortical movement of thefluid in one of said chambers and reduced vortical movement of the fluidin the other one of said chambers whereby the diflerence in the outputpressures from said sensors is related to the rate of rotation of saidcraft about said axis,

a fluid actuatable control device, and

means responsive to said output pressure difference and connected tosaid control device for actuating said control device in accordance withthe magnitude of said diflerence.

15. Control apparatus according to claim 14 wherein said means connectedto said control device includes a pair of fluid amplifiers each of whichis operatively associated with one of said rate sensors.

16. Control apparatus according to claim 15 wherein said control devicecomprises a control arm and means forming bellows chambers disposed onopposite sides of said arm so that differential expansion of saidchambers causes movement of said arm, and means connecting each of saidbellows chambers to one of said fluid amplifiers.

References Cited UNITED STATES PATENTS 1,141,631 6/1915 Hayes 73-2143,216,439 11/ 1965 Manion.

3,203,237 8/1965 Ogren 137-815 3,254,864 6/1966 Kent et a1 244783,276,259 10/1966 Bowles et al. 73-196 X 3,290,947 12/1966 Reilly 137-81.5 3,372,596 3/1968' Keller 73505 OTHER REFERENCES ControlEngineering, September 1964, pp. 73, 76, 99 and 100.

ANDREW H. FARRELL, Primary Examiner US. Cl. X.'R. 13781.5

